* {
  padding: 0;
  margin: 0;
  box-sizing: border-box;
}
html,
body {
  scroll-behavior: smooth;
}
.banner {
  width: 100%;
  height: 100vh;
  border: 1px solid red;
  position: relative;
  overflow: hidden;
}
.banner .index {
  display: flex;
  flex-direction: row;
  justify-content: flex-start;
  transition: 800ms;
}
.banner .index .index-img {
  width: 100vw;
  height: 100vh;
  overflow: hidden;
  background-repeat: no-repeat;
  background-position: center;
  background-size: cover;
}
.banner #top {
  display: flex;
  justify-content: center;
  align-items: center;
  position: absolute;
  width: 60px;
  height: 60px;
  top: 50%;
  left: 5%;
  transform: translateY(-50%);
  font-size: 48px;
  color: white;
  background-color: rgba(0, 0, 0, 0.6);
  border-radius: 50%;
}
.banner #bottom {
  display: flex;
  justify-content: center;
  align-items: center;
  position: absolute;
  width: 60px;
  height: 60px;
  top: 50%;
  right: 5%;
  transform: translateY(-50%);
  font-size: 48px;
  color: white;
  background-color: rgba(0, 0, 0, 0.6);
  border-radius: 50%;
}
.banner #xuanze {
  display: flex;
  list-style: none;
  position: absolute;
  bottom: 50px;
  left: 50%;
  transform: translateX(-50%);
}
.banner #xuanze > li {
  width: 20px;
  height: 20px;
  background-color: white;
  margin-right: 15px;
  border-radius: 50%;
}
.banner #xuanze > li:last-child {
  margin-right: 0;
}
